Disclosed herein are phase change inks and methods for the use thereof. More specifically, disclosed herein are phase change inks containing ester-amide materials and monoamide materials and used in indirect printing processes. One embodiment is directed to a phase change ink composition comprising (1) an ink carrier comprising (A) a first component which comprises an ester-amide material, and (B) a second component which comprises either (i) a material selected from the group consisting of urethane compounds, urea compounds, urethane-urea compounds, and mixtures thereof, (ii) a polyalkylene wax, or (iii) a mixture thereof; and (2) a colorant. Another embodiment is directed to a process which comprises (a) incorporating into an ink jet printing apparatus a phase change ink composition comprising (1) an ink carrier comprising (A) a first component which comprises an ester-amide material, and (B) a second component which comprises either (i) a material selected from the group consisting of urethane compounds, urea compounds, urethane-urea compounds, and mixtures thereof, (ii) a polyalkylene wax, or (iii) a mixture thereof; and (2) a colorant; (b) melting the ink; (c) causing droplets of the melted ink to be ejected in an imagewise pattern onto an intermediate transfer member; and (d) transferring the ink in the imagewise pattern from the intermediate transfer member to a final recording substrate.
In general, phase change inks (sometimes referred to as “hot melt inks”) are in the solid phase at ambient temperature, but exist in the liquid phase at the elevated operating temperature of an ink jet printing device. At the jet operating temperature, droplets of liquid ink are ejected from the printing device and, when the ink droplets contact the surface of the recording substrate, either directly or via an intermediate heated transfer belt or drum, they quickly solidify to form a predetermined pattern of solidified ink drops. Phase change inks have also been used in other printing technologies, such as gravure printing, as disclosed in, for example, U.S. Pat. No. 5,496,879 and German Patent Publications DE 4205636AL and DE 4205713AL, the disclosures of each of which are totally incorporated herein by reference.
Phase change inks for color printing typically comprise a phase change ink carrier composition which is combined with a phase change ink compatible colorant. In a specific embodiment, a series of colored phase change inks can be formed by combining ink carrier compositions with compatible subtractive primary colorants. The subtractive primary colored phase change inks can comprise four component dyes, namely, cyan, magenta, yellow and black, although the inks are not limited to these four colors. These subtractive primary colored inks can be formed by using a single dye or a mixture of dyes. For example, magenta can be obtained by using a mixture of Solvent Red Dyes or a composite black can be obtained by mixing several dyes. U.S. Pat. No. 4,889,560, U.S. Pat. No. 4,889,761, and U.S. Pat. No. 5,372,852, the disclosures of each of which are totally incorporated herein by reference, teach that the subtractive primary colorants employed can comprise dyes from the classes of Color Index (C.I.) Solvent Dyes, Disperse Dyes, modified Acid and Direct Dyes, and Basic Dyes. The colorants can also include pigments, as disclosed in, for example, U.S. Pat. No. 5,221,335, the disclosure of which is totally incorporated herein by reference. U.S. Pat. No. 5,621,022, the disclosure of which is totally incorporated herein by reference, discloses the use of a specific class of polymeric dyes in phase change ink compositions.
Phase change inks have also been used for applications such as postal marking, industrial marking, and labelling.
Phase change inks are desirable for ink jet printers because they remain in a solid phase at room temperature during shipping, long term storage, and the like. In addition, the problems associated with nozzle clogging as a result of ink evaporation with liquid ink jet inks are largely eliminated, thereby improving the reliability of the ink jet printing. Further, in phase change ink jet printers wherein the ink droplets are applied directly onto the final recording substrate (for example, paper, transparency material, and the like), the droplets solidify immediately upon contact with the substrate, so that migration of ink along the printing medium is prevented and dot quality is improved.
Compositions suitable for use as phase change ink carrier compositions are known. Some representative examples of references disclosing such materials include U.S. Pat. No. 3,653,932, U.S. Pat. No. 4,390,369, U.S. Pat. No. 4,484,948, U.S. Pat. No. 4,684,956, U.S. Pat. No. 4,851,045, U.S. Pat. No. 4,889,560, U.S. Pat. No. 5,006,170, U.S. Pat. No. 5,151,120, U.S. Pat. No. 5,372,852, U.S. Pat. No. 5,496,879, European Patent Publication 0187352, European Patent Publication 0206286, German Patent Publication DE 4205636AL, German Patent Publication DE 4205713AL, and PCT Patent Application WO 94/04619, the disclosures of each of which are totally incorporated herein by reference. Suitable carrier materials can include paraffins, microcrystalline waxes, polyethylene waxes, ester waxes, fatty acids and other waxy materials, fatty amide containing materials, sulfonamide materials, resinous materials made from different natural sources (tall oil rosins and rosin esters, for example), and many synthetic resins, oligomers, polymers, and copolymers.
U.S. Pat. No. 5,863,319 (Baker et al.), the disclosure of which is totally incorporated herein by reference, discloses a thermally stable ink for use in ink jet printing containing an ester amide resin, a tackifying resin, and a colorant.
U.S. Pat. No. 5,783,657 (Paviin et al.), the disclosure of which is totally incorporated herein by reference, discloses a low molecular weight, ester-terminated polyamide that may be blended with a liquid hydrocarbon to form a transparent composition having gel consistency. The ester-terminated polyamide is prepared by reacting “x” equivalents of dicarboxylic acid wherein at least 50 percent of those equivalents are from polymerized fatty acid, “y” equivalents of diamine such as ethylene diamine, and “z” equivalents of monoalcohol having at least 4 carbon atoms. The stoichiometry of the reaction mixture is such that 0.9≦{x/(y+z)}≦1.1 and 0.1≦{z/(y+z)}≦0.7. The reactants are heated until they reach reaction equilibrium. The gel contains about 5 to 50 percent ester-terminated polyamide, with the remainder preferably being pure hydrocarbon. The gels are useful in formulating personal care products and other articles wherein some degree of gel-like or self-supporting consistency is desired.
U.S. Pat. No. 5,645,632 (Pavlin), the disclosure of which is totally incorporated herein by reference, discloses solid diesters for hot-melt inks prepared by reaction of polymerized fatty acid with long chain primary monohydric alcohols, optionally in the presence of diamine. The long chain alcohols have at least about 20 carbon atoms, and preferably have 24 or more carbon atoms. The esterification of liquid polymerized fatty acid with monohydric alcohol provides a diester that is solid at room temperature and has a melting point of less than about 150° C. The diester can be formulated with colorants and/or other image-producing materials to provide an ink for hot-melt printing, e.g., hot-melt ink jet, gravure or intaglio printing.
U.S. Pat. No. 5,194,638 (Frihart et al.), the disclosure of which is totally incorporated herein by reference, discloses a resinous binder for use in hot melt ink compositions, which ink compositions may be used in hot melt ink jet printing applications. The resinous binder has a melt viscosity of 250 cps or less at 150° C., is sufficiently transparent to allow a colorant to be distributed through the resinous binder in an amount effective to impart a predetermined color to the resulting hot melt ink composition, and has a blocking temperature greater than 100° C.
U.S. Pat. No. 4,889,560 (Jaeger et al.), the disclosure of which is totally incorporated herein by reference, discloses a phase change ink carrier composition combined with a compatible colorant to form a phase change ink composition. A thin film of substantially uniform thickness of that phase change ink carrier composition, and the ink produced therefrom, has a high degree of lightness and chroma. The thin films of a substantially uniform thickness of the ink composition are also rectilinearly light transmissive. The carrier composition is preferably a fatty amide-containing compound.
U.S. Pat. No. 4,066,585 (Schepp et al.), the disclosure of which is totally incorporated herein by reference, discloses intaglio and flexographic printing processes employing solvent-free inks, solid at room temperature but molten at printing temperatures, and inks suitable therefor, said inks comprising a pigment and a thermoplastic binder having a softening point between 90° C. and 160° C., said binder comprising a synthetic polyamide resin or synthetic polyesteramide resin, each resin being the condensation product of (1) an acid component comprising a dimerized fatty acid and a monocarboxylic acid and (2) an amine component comprising a diamine and, in the case of the polyesteramide resin, additionally comprising a diol and/or alkanolamine.
U.S. Pat. No. 3,622,604 (Drawert et al.), the disclosure of which is totally incorporated herein by reference, discloses synthetic polyamides, useful as binders in the formulation of printing inks, formed between a dimeric fatty acid, an unsubstituted lower aliphatic monocarboxylic acid, ethylene diamine, and certain aromatic, cycloaliphatic, and other aliphatic diamines, including aliphatic ether diamines, and methods for preparing such polyamides.
U.S. Pat. No. 3,253,940 (Floyd et al.), the disclosure of which is totally incorporated herein by reference, discloses polyamide resins and solutions thereof suitable for use as flexographic ink vehicles and alcohol solutions of polyamides obtained by reacting a mixture containing polymeric fat acids, alkylene polyamines, and a low aliphatic monobasic acid.
U.S. Pat. No. 4,830,671 (Frihart et al.), the disclosure of which is totally incorporated herein by reference, discloses an ink composition having the properties of stability and uniformity of performance under ink jet printing conditions and desired printing properties that can be obtained with hot melt ink compositions consisting of a resinous binder comprising a compound of the formula wherein R1 represents a polymerized fatty acid residue with two carboxylic acid groups removed, R2 and R3 are the same or different and each represent an alkylene with up to 12 carbon atoms, a cycloalkylene with 6 to 12 carbon atoms, an arylene with 6 to 12 carbon atoms or an alkarylene with 7 to 12 carbon atoms, and R4 and R5 are the same or different and each represents an alkyl having up to 36 carbon atoms, a cycloalkyl having up to 36 carbon atoms, an aryl having up to 36 carbon atoms, or an alkaryl having up to 36 carbon atoms, said resinous binder having a melt viscosity of less than 250 CPS at 50° C. and a colorant distributed through the resinous binder in an effective amount sufficient to impart a predetermined color to the resulting hot melt ink composition.
U.S. Pat. No. 5,389,958 (Bui et al.), the disclosure of which is totally incorporated herein by reference, discloses a method and the apparatus for employing the method whereby an intermediate transfer surface of a layer of sacrificial liquid is applied to a supporting surface and a phase change ink is deposited on the liquid layer. The inked image is then contact transferred to a final receiving substrate.
U.S. Pat. No. 6,174,937 (Banning et al.), the disclosure of which is totally incorporated herein by reference, discloses a phase change ink comprising a material of the formula wherein X1, X2, X3, and X4 are segments comprising atoms selected from groups V and VI of the periodic table; wherein at least one R1 and R5 comprises at least 37 carbon units; and wherein R2, R3, and R4 each comprise at least one carbon unit. The invention further encompasses a composition of matter, as well as methods of reducing coefficients of friction of phase change ink formulations.
U.S. Pat. No. 6,471,758 (Kelderman et al.), the disclosure of which is totally incorporated herein by reference, discloses an ink composition for a meltable ink usable in a printing device in which ink drops are ejected from ink ducts, which comprises agents which reversibly cross-link the ink, the said agents containing a gelling agent. When an ink drop which has been transferred to a substrate passes over into a gel during the cooling process, the consequence is that the viscosity of the melted ink drop increases greatly so that the drops become relatively immobile. In this way the ink drops are prevented from uncontrollably flowing into the paper. As a result, inks of this kind are suitable for use on both porous and smooth substrates. In addition, these inks have been found suitable for use in a printing device in which printed substrates are subjected to thermal after-treatment.
European Patent Publication 1 378 551 (Kremers et al.), the disclosure of which is totally incorporated herein by reference, discloses a meltable ink which is solid at room temperature, which ink is suitable for use in an indirect printing process, in which printing process the ink is transferred, by the use of an inkjet printhead, to a transfer element, whereafter the ink is transferred to a receiving material under pressure from the transfer element, said ink having a composition such that it is pressure-transferable at a temperature between a bottom limit and a top limit, characterised in that the ink has a deformation energy of less than 20×105 Pa·s at a temperature equal to the top limit.
While known compositions are suitable for their intended purposes, a need remains for improved phase change inks. In addition, a need remains for phase change inks wherein the ingredients thereof exhibit good miscibility with each other. Further, a need remains for phase change inks that exhibit good color strength. Additionally, a need remains for phase change inks that print successfully on paper and transparency stock. There is also a need for phase change inks that generate prints with good foldability characteristics. In addition, there is a need for phase change inks that generate prints with good performance in automatic document feeders. Further, there is a need for phase change inks that generate prints having a desirably low coefficient of friction.